Earth Windows


Earth Windows looks at the eruption from a geological point of view.



Ape Cave Exploration


Goal: To provide students with an understanding of lava-tube formation, and the geological and ecological features of the Ape Cave ecosytem.

Objectives: Student will demonstrate ability to:

  1. Describe how a lava tube forms.
  2. Recognize the niche occupied by several life-forms
  3. surviving in this specialized ecosystem.
  4. Locate, sketch and identify sources of five of Ape Cave's geological features.
  5. Appreciate the necessity of protecting such delicate ecological systems, taking proper safety precautions, and observing behavioral rules during their small-group exploration of Ape Cave.


Key Concepts: A lava flow may travel great distances, creating unique geological features and ecosystems because of its self-insulating properties. Lava tubes represent a fragile, specialized habitat requiring care and respect on the part of huma n visitors.

Summary: Students simulate the formation of Ape Cave, in order to better understand its construction. Students observe, illustrate and discuss geological features of this lava tube. The teacher provides instruction in preserving ecosystem balanc e, and the effects of human vandalism on Ape Cave.

Content Areas: Geology, speleology, biology, ecology, environmental studies, art.

Materials Needed:



Needed supplies and equipment:

  • lanterns
  • flashlights
  • jackets
  • hats
  • sturdy shoes
  • trash bags for litter-collection

(A teacher/student ratio of 1:8 is advised for this field activity.)

Evaluation: Participation in simulation activity, completion of Geological Features activity-sheet, appropriate conduct reflecting respect and appreciation.

Instructional Sequence:

  1. As you travel to Ape Cape, have students draw a cross-section of the bus, in order to practice this skill.


  2. Also on the bus, review key characteristics of a lava flow.


  3. Liken the bus to the magma chamber of Mount St. Helens, with the doors of the bus representing the vent through which lava was emitted.


  4. Point-out the "features" of the cave represented in the simulation (tube, skylights, breakdown, flow-through,) and discuss.


  5. Explain the Geological Features activity-sheet and give instructions for its completion.


  6. At the entrance to Ape Cave, discuss:


    • When it was formed.
    • Who discovered it, and how.
    • How the cave got its name.
    • Proper cave-exploration behavior: respect for all features, no running, quiet voices, lights on all times and kept out of people's eyes, remaining in groups of four.


  7. Divide class into "explorer groups" of four students each. Assign at least one adult per two groups of four. Send half the groups upslope (beneath stairs) for ten minutes, to identify and sketch the tube-in-tube, lavacicles, ceiling breakdown. Send the other half downslope for ten minutes to identify and sketch flow-mark s, wall breakdown. Reverse the groups' locations and assignments for the second ten minutes.


  8. Gather groups together at the bottom of the stairs to share what they have found. Assign to each group a geological feature, which they will discuss among themselves for a few minutes and then present to the whole class, or on which they will later h ave an opportunity to become "experts" for a school-site presentation.


  9. To conclude this activity, take the class back to the cave entrance. Discuss food-chains within the cave, and how the cave's food-chain is connected with the one outside the cave. Discuss evidence of vandalism and students' feelings about it. (See questions at bottom of Geological Features handout.)



  1. Repeat lava-flow simulation now that its effects have been observed in the cave


  2. Study spelunking and plan a longer trip in which the class explores more of the cave's length


  3. Walk The Trail of Two Forests at the Lava Cast Picnic Area


  4. Read Ape Cave and the Mount St. Helens Apes, by William R. Halliday



Lava Falls Walk


Goal: To acquaint students with the unique geological features of the Mount St. Helens lahar.

Objectives: Students will

  1. Observe dramatic effects of the 1980 Mount St. Helens eruption
  2. Participate effectively in a cooperative group task
  3. Focus their attention on and identify selected features of this landscape
  4. Appreciate their own impact on natural features and landscapes

Concept: Dramatic geological events shape the earth in ways that may seem ordinary and indiscernible to the untrained eye. These events also leave behind extraordinary puzzles and anomalies. From some of those created by the recent eruption, we can learn much that is new about the nature and power of volcanic activity.

Summary: Students look for, identify and sketch six selected features of the lahar they will encounter on a 40-minute walk. They are encouraged to participate actively in small-group exploration and examination, and engage in creative interpretation, in order to fully experience the richness of this environment.

Content Areas: Science (geology), art

Materials Needed:


  1. Lava Falls Images
  2. pencils
  3. paper
  4. clipboards or notebooks

Teacher Narrative: A Lahar Tells a Story

Evaluation: Because the intent of this lesson is to encourage maximum engagement and creativity, and may serve to set the tone for other study activities on the lahar (see the Disturbance Ecology Lessons), formal grading is not recommended.

Instructional Sequence:

  1. Gather students in the parking lot as they leave the bus. Identify landmarks: Lava Canyon, the lahar, Mt. Adams, Hood, Rainer, the blast zone, Shoestring Glacier, etc. Give instructions for protecting this ecologically sensitive area. ("Take nothing but pictures; leave nothing but footprints!") Read aloud the narrative which follows.


  2. Introduce the Lava Falls Images activity handout. Reassure students that artistic talent is not required, and that sketches may be accompanied by descriptive narrative. Remind them to walk carefully and minimize disturbance to the environment. Each student will need to find one example of each item on the handout; however, no one is expected to do so without the assistance of others. They should confer, share ideas, point-out "discoveries" to each other, etc.


  3. Accompany the students and circulate among them, but tell them they are "on their own" in terms of finding answers. Their findings and conclusions, ideas and questions will be addressed in the follow-up discussion.


  4. Following the walk, reassemble the students to share their drawings and discuss their findings. For the benefit of those unable to identify the assigned features, retrace your steps, pointing-out and explaining all six.

Time and Time Again: A Stratigraphy Activity


Goal: To provide students with opportunity to observe the record of 13,000 years of Mount St. Helens history at a cliff on the lahar which reveals stratigraphic bands, and to impress upon them the immensity of geologic time.

Objectives: Students will demonstrate

  1. Understanding of the cyclic and varied nature of volcanic activity


  2. Understanding of the ways in which these varied forms of activity help to determine the surrounding topography


  3. Ability to differentiate and describe various layers of deposition


  4. Appreciation of the challenges faced by geologists in the tracing of natural history.

Key Concepts: Volcanic activity constructs topography. Volcanic eruptions have been varied in form, and will continue to occur in a variety of ways. The stratigraphic layers at Mount St. Helens help to reveal its history, and aid in predicting its future.

Summary: At the stratigraphic bands site, the teacher will lower from the top of a low cliff a series of signs, fastened at intervals to a rope, which are maintained in that location and mark the strata revealed there. Students observe, describe characteristics and record evidence of six of Mount St. Helens' eruptive periods. They identify specific traits of lahars, pyroclastic flows, and airfall found in stratigraphic depositions from these periods.

Content Areas: Earth Science, History

Materials Needed:


  1. Stratigraphic Bands Activity Worksheet
  2. Stratigraphic Bands Activity Key
  3. Summary of Geological History
  4. pencils
  5. paper
  6. clipboards or notebooks

See also Classroom Supplements folders.

Evaluation: Completed, corrected worksheet may be used to study for quiz or project on eruptive periods.

Instructional Sequence:

  1. Lower and arrange signs at the stratigraphic bands site, and explain to students that the signs identify layers corresponding to the six eruptive periods on their worksheets. Point out that the distance between knots on the rope is one foot. Note that the bands revealed here account for only the last 13,000 years of the 40,000 years of volcanic activity presently identified, and that inter-pretations of the evidence are, by nature, speculative.
  2. Explain how to complete the Stratigraphic Bands Activity worksheet, to include thickness, description of eruptive material, and artifacts of plant and animal life contained in the layers.
  3. Discuss the challenges of determining what each layer represents, the cyclic nature of Mount St. Helens eruptive activity, and the use of examination of past depositions to predict future eruptions.
  4. Ask questions to stimulate thinking, such as what root artifacts in the layers can tell us about former environments; what the layers reveal about how lakes in the area were formed, etc.
  5. Give the group ample time to complete and to discuss the questions at the bottom of the worksheet. It is imperative that the teacher move from group to group during this time to address concerns and answer questions. Have the group suggest mnemonic devices -- image associations, limericks, phrases, acronyms, etc. -- as aids to remembering the names of the periods in order.


Extension Activity:


  1. Correlate this activity with the "A Place in Time" activity and dates of volcanic eruptions with concurrent events in world history.